Stereoscopic shift



Nov. 7, 1939. w. BADER Er AL 2,178,867

STEREOSCOPIC SHIFT Fi led May 4, 195a ATTORN Patented Nov. 7, 1939 UNITED s'mr T orrics C STEREOSCOPIC SHIFT a corporation of Ohio Application May 4, 1938, Serial No. 206,023

11 Claims.

This invention relates to a stereoscopic shift mechanism of the kind used in radiographic apparatus to make stereo-radiographs.

The object of the invention is the provision 01. an improved register-adjusting and locking means for that type of X-ray apparatus known as a pendulum cassette changer. The state of the art previous to this invention is illustrated by U. S. Patent #l,622,320-March 29, 1927, to J. R. Kelley.

In machines of the general type described in the patent, the extent and speed of pendulum travel were regulated by the manual adjustment or shifting of a weight connected to the pendulum. Regulation of the position of this weight had to be such that the second cassette and its carriage would be urged with just enough force into the position for stereo-radiography and there be locked. Too much force would interfere with the proper locking or register and also would set up very undesirable vibration in the apparatus, i. e., substantially as high at the end of the swing as at the beginning.

More specifically therefore, the present invention is concerned with the avoidance .of delicate manual adjustment of the weight for each different size and weight of cassette, which process was tedious and uncertain. This invention also aims to make the locking certain, practically vi- .brationless and to have one setting adapted to a reasonable variation in the weights of the eassettes to be shifted.

Briefly stated, the steps followed by the mechanism of the invention comprise bringing an iron weight mounted on the pendulum mechanism into the field of solenoid coil, then energizing the coil by the action of the pendulum, whereby the coil will attract the weight to complete, smoothly and certainly, the intended travel of the second cassette and its carriage to a locked position exactly in stereo-register.

In the drawing, Fig. 1 shows the subject matter of my invention mounted upon a pendulum cassette changer, which is shown fragmentarily in rear elevation.

Fig. 2 is an enlarged detail of Fig. 1 showing the solenoid coil in section and the position of the pendulum before and after the shift in full and dotted line respectively.

Referring now especially to Fig. l, Ill-l3 are the metal uprights of a pendulum type cassette changer, H the metal framework of a carriage movable vertically on said uprights, H! the customary lead and Bakelite shield, I3 a tie piece connecting the uprights, M a, pulley on the latter,

W a chain movable over the pulley and IS a counterweight balancing the carriage H and all of its accessories. v

Shown shifted toward the right side of the drawing is the conventional pendulum mechanism which comprises two pendulum shafts l1 pivoted to the carriage framework which, slides verticallyon uprights Ill and H and carries the conventional cassette holder l8, withinwhich are supported cassettes 59. The left hand or No. l

cassette is shown aligned within the opening 29 of the shield l3 so that the X-ray can strike it. As shown, the cassette holder is ready to swing upon the release ofa spring pressed detent 2! of an electromagnet 22from a notch 23, one of which is cut into each of gently sloping cams 24 carried on the lower edge of the cassette holds er below the center of each cassette therein. So much of the structure as has been described is conventional and no novelty is claimed for :it.

Attached to left. hand upright H3 is my mechanism for urging the cassette holder it into locked position; said mechanism being shown locking the cassette holder in Fig. l and is denoted in general by 25.

.In Fig. 2, I5 is the left-hand upright. That part of the carriage frame H behind the mechanism 25 of Fig. 1 serves as a shelf for the purpose of pivotably mounting the left-hand pendulum shaft l7. Rigidly attached to the hub v2E5 of the pendulum shaftis a plate 27 to which-is rigidly bolted a half-circle of brass rod 28 which bears two iron weights 29 encircling it, the position of which upon the rod is adjusted at the factory so that the user need not concern-himself about it. The purpose of having two weights is to provide for the operation of the device in two directions, i. e., right to left'and left to right. For this reason, the weights are separated about 90. The plate Z'l is normally tilted at about a 45 angle either to left .or right depending upon the side to which the cassette holder has been shifted. Mounted on the carriage frame ll below the point at which the left hand pendulum shaft ll is pivoted, there is a magnet spool 36, the coils of which are wound upon a hollow brass core 3|. The opening thru thiscore is ample to admit the rod 28 and the weights 29. The mounting of the core 3| is such that it encircles the rod 28 at all times. Theelectrical winding of the magnet spool is so arranged that when the cassette holder is at the right side as shown, an attracting force will be exercised upon the right hand weight increasingly as it nears the spool. For this purpose ,of energizing the magnet at one time and de-energizing it at other times, a switch 32 is mounted above the spool 30 in the position shown. It may be mounted on the outer case 33 of spool 36, or it may be mounted upon the carriage frame II. This is possible because the pendulum arms are arranged to swing between the carriage frame ,I l and the shield 18 which is supported from the carriage frame H by a light upper framework 34. The pendulum arms thus have a free path. No mountings for the switch 32 are shown because they would merely obscure the details of the drawing.

The switch comprises a cylindrical case within which there are two spring brass contacts. These bear against. a slidable rod 36, the middle section of which is brass, the outer sections Bakelite. There is a Bakelite button at each end. The proportioning is such that when one of the spring steel fingers 31 carried upon the under side of plate 21 pushes the end button of rod 36, the magnet spool 30 is actuated only when the brass section of the rod is passing the contacts 35. 4

This happens when the weights 29 are, on or the other, within the range of attraction of the magnet spool. As the plate 21 departs from levelness and reaches a position shown in Figure 2 or its other extreme of travel the spring finder 31 on the opposite end of the plate pushes the rod 36 out of electrical contact with and conduction thru the brass section and so de-energizes the magnet spool. Consequently the weight which is inside the spool is not as hard to push out as if the current were on. Alternating cur rent, preferably 60 cycle, is used in the magnet circuit, so the influence developed by this type of current is to. center the weight within the spool and to hold it there. From the foregoing, it will be evident thatthe action is free durin the first part of the swing of the pendulum shafts and as the swing nears completion the weight is drawn inward into the spool until it reaches the approximate middle thereof, at which time the current is cut off. It is also evident that this action is provided for regardless of whether the swing is from left to right or right to left.

The natural momentum of the swing of the pendulum arms and cassette holder is almost suflicient to carry the holder from one notch in cam 24 to the other. The auxiliary electromagnetic action just described is relied upon to urge the cassette holder just a short distance into registry in the notch 23 shown cut into the cam 24.

Holding the cassette holder in registry is a function performed by the detent 2| and the apparatus is set in motion by withdrawing it from the notch 23 by the action of the electromagnet 22 which pulls the sear 2| down. The swing of the pendulum shafts and cassette holder then takes place and when the furthest cam 24 has almost reached registry with the sear 21 the 1 spool 30 attracts the downcoming weight 29, which pull is transmitted thru rod 28, plate 21 and pendulum shaft I! to the cassette holder. This shifts the latter gently to the position of registry with the second cassette in line with the opening 20. The spring of sear 2| then presses up the latter into locked position. This is possible because the current has been turned off manually from electromagnet 22 as soon as the cassette holder started to swing.

Loading and unloading of the cassettes is in the conventional manner.

In the appended claims, "non-ferrous means done not made of a material which can be attracted or repelled by a magnet.

Radiographic position means one of the vertical positions assumed by the cassettes at either end of the arc of travel, one position being substantially as high as the other.

I claim as my invention:

1. A stereoscopic shift mechanism comprising the uprights of a frame, a cassette holder slidable vertically thereon, a plurality of pendulum shafts pivoted at the top of the cassette holder adjacent the uprights to permit said cassette holder to swing, a plate mounted at substantially a right angle to one of said pendulum shafts near its pivotal point and mounted at to said shaft, a magnet spool mounted on the said cassette changer adjacent the same upright bearing said p1ate,-a semicircular non-ferrous rod mounted below the said plate and attached thereto, said rod passing thru said magnet spool, a plurality of ferrous weights mounted on said semicircular rod, a pair of spring fingers mounted below said plate and on said plate and a switch actuable by said spring fingers to reciprocate to energize said magnet spool temporarily near the end of the swings of said plate.

2. The combination set forth in claim 1 having in addition a plurality of gently sloping cams on the lower edge of thecassette holder, said cams each bearing a notch, and a stationary electromagnet, said magnet controlling a detent adapted to fit each of said notches.

3. In a stereoscopic shift of the class wherein acassette holder swings as a pendulum to a locked position at the end of an are substantially as high as the starting point, the combination with said cassette holder of a pendulum shaft, a plate mounted on said shaft, a semicircular nonmagnetic rod mounted on said plate, ferrous weights on said rod and a magnet spool encircling said rod and electrical control means including reciprocable switch actuable by said pendulum shaft to energize said magnet spool to gently complete the swing of said cassette holder to a position at the opposite end of its arc substantially as high as its starting point by the magnetic influence of said spool upon said ferrous weights.

4. The combination set forth in claim 3 having in addition a plurality of cams on the lower edge of the cassette holder, said cams each bearing a notch, and an electromagnet mounted on a nonswingable part of the cassette holder, said magnet having a detent adapted to fit each of said notches.

5. In a stereoscopic shift apparatus comprising the uprights of a frame, a cassette holder slidable vertically thereon, a plurality of pendulum shafts pivoted at the top of said cassette holder adjacent the uprights, a plate mounted on one of said pendulum shafts at substantially right angles thereto, switch actuating fingers mounted near the ends of said plate, a semicircular non-ferrous shaft, a three-position electrical switch mounted below said plate and adapted to be actuated by said fingers and alternating-current powered electromagnetic means controlled by said switch mounted so as to enclose said nonferrous shaft and capable of forcibly attracting or repelling said weights so as to enable said cassette holder when the latter is released to swing from said pendulum shafts gently to complete the swing to a position at the opposite end of the arc of swing substantially as high as the starting position ofthe cassette holder.

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6. The combination set forth in claim having in addition a plurality of cams on the lower edge of the cassette holder, said cams each bearing a notch, and an electromagnet mounted on a nonswingable part of the cassette holder, said magnet having a detent adapted to fit each of said notches.

7. A stereoscopic shift apparatus including a cassette holder which is swingable in an arc, arms for holding said holder while swinging, an electromagnet, a core for said electromagnet, a detent on an end of said core, notches on said cassette holder into which said detent fits and means for lifting said cassette holder when loaded with cassettes, electromagnetically to a position at the end of its swing which position is substantially as high as the starting point of said swing.

8. In an apparatus of the class described, a frame, a cassette holder swingably mounted on said frame, a plurality of arms pivotably suspending said cassette holder for swinging from said frame, a plurality of cams on the lower edge of said cassette holder, a notch on each cam, means including a detent for co-operating with the notches of said cams to lock said cassette holder in a position in which a cassette contained in the latter would be in a position to intercept an X-ray beam, means including an electromagnet mounted on said frame for urging said cassette holder into a position in which a detent may look it and a plurality of ferrous weights, a non-magnetic curved rod bearing said weights, said rod passing through said electromagnet, and a reciprocatable mounting for said rod, said mounting being attached to said frame.

9. The combination set forth in claim 8 in which comprises an electromagnet having a spool, a trigger switch adapted to energize said magnet spool and means adapted to actuate said trigger switch-from the forceof the swing of said casarms and swingable as a pendulum, a plurality of cams on the lower edge of said cassette holder, a notch in each cam, means for locking said cassette holder at the ends of its swing into a position in which a cassette contained within it can intercept an X-ray beam, said means including an electromagnet, a detent controlled thereby and co-operating with the notches of said cams, and urging means for forcing said cassette holder into locked position, said means including anelectromagnet having a hollow spool, a switch controlling the spool, a curved non-magnetizable rod passing through said spool, a plurality of magnetizable weights carried upon said rod at intervals thereof and a plate upon which said rod is mounted, said plate being arranged to transmit mechanically the force of the electromagnet to the cassette holder.

11. The combination according to claim 10,

spring contacts on said plate, said contacts being adapted to shift said switch toward the end of the swing of said cassette holder and so and then de-energize said electromagnet spool.

WILLIAM BADER. RUDOLPH LICHER. 

